Added iMSCP_Events_Aggregator
Changed: EventManager is no longer static (shared). The getInstance() method is now deprecated. It now return an
		iMSCP_Events_Aggregator instance to ensure backward compatibility with plugins which are already released
Changed: Implementation of the register() method is no longer mandatory in action plugins
Deprecated: iMSCP_Events_Manager::getInstance() (will be removed in next minor version)
Fixed: Plugin manager must have its own eventManager
Fixed: Plugin event listeners are registered twice in some contexts
Updated: Plugin API to version 0.2.9 (changes are backward compatible)